Tokina's 12-28mm f/4.0 AT-X Pro APS-C Lens for Canon from has a maximum aperture of f/4.0 and is a wide-angle to standard lens. Compatible with Canon APS-C cameras, it has a 35mm focal length equivalency of 19-45mm.

The Tokina Nikon F-mount AT-X 70-200mm f/4 PRO FX VCM-S Lens is a telephoto zoom lens designed for digital cameras with full-sized sensors as well as APS-C (DX) sensors and features a constant f/4 maximum aperture. ... Learn More

The 16-28 f/2.8 uses a newly developed silent DC motor which enables the lens to focus more rapidly and more quietly then previous iterations. The DC motor coupled with a new GMR (Giant Magnetoresistance) magnetic AF sensor work in conjunction with one another in order to increase AF Speed.

Tokina's 12-28mm f/4.0 AT-X Pro DX Lens for Nikon is a wide-angle to standard-length zoom with a maximum aperture of f/4.0. It provides a focal length equivalency of of 18-24mm. This lens boasts compatibility with Nikon DX cameras. ... Learn More

The 16-28 f/2.8 uses a newly developed silent DC motor which enables the lens to focus more rapidly and more quietly then previous iterations. The DC motor coupled with a new GMR (Giant Magnetoresistance) magnetic AF sensor work in conjunction with one another in order to increase AF Speed.